Electromagnetic interference or noise degrades optimum performance of electronic devices. For active implantable medical devices, such as pacemakers, defibrillators, neuromodulators, programmable infusion devices and the like, electromagnetic interference may create potentially dangerous situations. Accordingly, a good deal of care is taken to shield or decouple device electrical components from noise in an effort to maintain a high level of reliable performance.
One source of noise can arise from capacitive coupling between metallic housings of implantable medical devices and inductive coils, such as telemetry antennas, disposed within the housings. Use of the housing as a return electrode for electrical signal generators operating in unipolar mode is one notable source of such noise.
Typically, such sources of noise are minimized by employing conductive spray coating or adhesive conductive shields to surround the inductive telemetry antenna coil in a Faraday cage like manner. However, such materials are often difficult to work with from a manufacturing perspective and may suffer from reliability and variability.